Whatever the reason for your need to wear a back brace, you don't necessarily want it to be noticeable. Although it may seem a daunting prospect, it's pretty easy to find attractive clothing that will hide your brace, and you can also guide attention away from it by using accessories such as hats, belts, scarves or jewelry.
Just remember comfort, disguise, and distraction.
Always wear something under the brace to prevent chafing. A tank top or spaghetti strap top with some Lycra works well. Avoid tops made from 100% cotton as they can lose their shape after washing, which can result in bunching and irritation to your skin.
Be prepared to spend some time trying on clothes. Also, check the labels; you don't want to buy clothes that will shrink. And when you find a style or brand that works well with your brace, stick with it.
First of all, try on what you already have. You might be surprised at what you can still wear. Bear in mind that darker colors and patterns help disguise any lumpiness.
Just about any top will look fine if some kind of jacket or cover up is worn over it. The warmer months can be a little trickier, but lightweight cardigans or cropped jackets (especially if they have pleating or gathering along the back yoke) will cover the straps and allow you to wear any top you like underneath.
If you don't want to wear a jacket, any clothes with some volume will work. Just avoid tight tops. For women, look for anything swingy, fluid, or full, whether it's a dress or pair of pants. Empire waist or A-line dresses will skim over the brace. (You can wear a slip under the dress so the brace straps don't snag it.) Dresses that have a full skirt and defined waist are great. A bandeau is useful if low armholes expose the brace. Skirts that swing, with layers, flounces, or ruffles, distract and disguise. Avoid miniskirts: without a thick waistband or belt to hold them in place, they can ride up.
Try loose tops that extend down over the hips, worn over leggings. These can be worn loose, or cinched a belt or sash either at the waist or on the hips, positioned over a brace strap. Imagine an oversized sweater with leggings, great boots, a great necklace, and a great bag.
When looking for jeans or other pants, try different height waists for comfort and for what doesn't draw attention. You may want to buy them in a longer length, to compensate for perhaps having to wear them higher on the waist. Avoid low-rise pants as they can get hitched under the bottom of the brace.
Bootleg and wide leg styles can balance the look of your legs. Flap-style back pockets help to give shape to the rear end and disguise any part of the brace that sticks out there. If there are no pockets, you could wear a tunic or short dress over the pants.
Bermuda shorts work well, but you might want to buy them one size larger. Short shorts ride up, so buy them a little longer than you want and they will be the right length when you wear them.
Above all, remember that wearing a back brace doesn't stop you looking great.